Adrian Cornelius Langerwerf was born in Waspik, Noord Brabant, in the Netherlands, on 15 September 1876, the son of Cornelius Langerwerf, a farmer, and his wife, Lucia Smeur. Feeling a call to be a missionary priest, he entered the Society of St Joseph for Foreign Missions. After philosophy studies at Roosendaal he went to London to study theology at St Joseph's Foreign Missionary College of the Sacred Heart, Mill Hill. There he was ordained priest on 21 September 1901.
Langerwerf arrived in New Zealand in December 1901. Following curacies at Whangaroa, Tokaanu and Rotorua he was appointed to Tokaanu–Waihi in 1905. Marist priests had been active in the area until the 1860s and a few resolute Maori catechists had kept the embers of faith alive, but the work was not systematically resumed until the 1880s when the Mill Hill fathers arrived in New Zealand. In 1889 the parish of Tokaanu–Waihi was set up under J. W. Smiers to serve the Taupo district. Smiers built a presbytery and the Church of St Werenfrid at Waihi, on the southern edge of Lake Taupo, and in 1904 Edward Bruning built a school and convent at Tokaanu.
Langerwerf made many arduous journeys on horseback from his base at Waihi, west to Taumarunui and north to Aria, Mokai and Taupo township. He was assisted by the Sisters of St Joseph of the Sacred Heart who arrived in 1905 to staff the school, which he shifted from Tokaanu to Waihi about 1910. Throughout his parish he built up a large and affectionate following. A swarthy, stocky man with a trim beard, Langerwerf was an eloquent speaker of Maori and was known to Ngati Tuwharetoa as Pa Ateriano.
Langerwerf worked strenuously to raise his people's living standards. He sought to dissuade young Maori from leaving the district in search of employment and a more comfortable way of life by providing these amenities locally. He began by encouraging landowners to clear their acres for farming and to smoke cows out of the bush to start dairy herds. Next, Waihi village was to have its own butter factory, financed with £6,000 gained from Maori land sales. To assist in this project, in 1918 Langerwerf persuaded Thomas Dempsey, a Piopio dairy plant supervisor, and his wife to shift to Waihi. Then, with a volunteer labour force, he constructed a road across the swamp from Tokaanu to Waihi, built a hydroelectric plant to supply power to the factory and to the village, and installed a water reticulation system. In 1919, in contrast to most of rural New Zealand, every home in Waihi is said to have had electricity, a flush toilet and running water. Cream was brought to the factory by pack-horse and boat, and the butter was carted out to the railhead at National Park.
Within a decade, however, this flourishing operation began to falter. By the 1920s many of the farmers were being tempted south to Ratana pa, attracted by the prophet Tahupotiki Wiremu Ratana. As the cream supply dwindled, Langerwerf looked to the bush for an alternative local industry. Since Ngati Tuwharetoa owned most of the timber between Waihi and Taumarunui he encouraged them to harvest it. In 1928 the dairy factory was closed and was converted into a timber mill; the Tuwharetoa Timber Corporation was formed to manage the operation. This functioned until the mid 1930s when better roads and the large-scale methods of the big timber companies moving into the district rendered it uneconomical. Power generation continued at Waihi until 1962.
It was not only through economic measures that Langerwerf sought to strengthen the allegiance of his flock and to counter the Ratana influence among them. He also worked to ground their faith more firmly in understanding, and he issued a booklet entitled Ko te waka o Hato Petera (The barque of St Peter) explaining Catholic doctrine. So well received was it that he began a periodical of the same name, the first issue of which appeared in 1929. The articles, redolent of his skill as an orator, took the form of an entertaining and informative dialogue between a non-Catholic Maori and a Catholic priest. Successive issues found an eager audience. Diagnosed in 1934 as having tuberculosis, Langerwerf was admitted early in 1935 to the Mater Misericordiae Hospital in Auckland, where he spent his last days dictating articles for Te Waka. He died there on 7 April 1935, and was buried beside the church at Waihi. His friend and ally Hoani Te Heuheu was later buried nearby.
Langerwerf was a missionary who had a notably broad view of his ministry. He established the Catholic church strongly among the people he served, and in improving their material conditions helped prepare them to profit from new opportunities for prosperity.